In our last update to Project Practical Performance, we covered the initial maintenance services of a PPI and a LIQUI MOLY Platinum oil change. In this update, I'm going to cover tackling the intake valve decarbonization we found it needed during the PPI.
(If some of the information below looks familiar, it's because I've already covered this information in our Gen 3 TSI Ultimate Maintenance guide and simply reposted some of it here)
The Carbon Buildup Issue
The 2.0T EA888 Gen 3 TSI engine found in the B9 Allroad, like the versions before it, utilizes direct injection technology for its fueling system. This means that instead of gasoline being sprayed into the intake ports and onto the intake valves (thereby cleaning them), it is instead sprayed directly into the combustion chamber. While this provides far more precise timing, providing more power and better fuel economy, it also has a major drawback in the form of carbon build-up. Many European versions of this engine utilize multi-port injection so that this issue doesn't occur, but in North America, we're not so lucky. Instead, the Gen 3 TSI engine we received is prone to carbon build-up on the intake valves.
Carbon Buildup Symptoms
The most noticeable symptom of carbon build-up is a rough idle, especially during cold starts. If the carbon build-up is substantive enough, your engine may feel as though it is having a slight mis-fire such as when the spark plugs need to be replaced. This can even register as a mis-fire in the ECU and cause a CEL to occur. A slight loss of power and a decrease in fuel economy may be experienced as well.
It's important to note that there is no set interval for when this service should be performed. If you think your engine is experiencing carbon build-up issues, and you have a good Audi or VW specialist shop in your area, you can always ask them to take a look at your intake valves. They can take a borescope (snake camera) and put it into the valves to check them out.
In addition, if you drive your car hard or have a long highway commute, you have a greater chance that you won't need a carbon cleaning as soon as someone that drives in stop and go traffic all the time. This is because carbon can be burned off when engine temps increase under hard driving or on long steady drive cycles. However, you cannot completely get rid of the carbon by simply driving your car hard; there will still be some build-up that remains on the intake valves. In some situations this build-up can become harder when it is essentially "baked" more in the hot engine.
Carbon Buildup Solution
Unfortunately the only way to properly clean carbon build-up is to remove the intake manifold and physically remove the build-up. We've found that the most effective way to perform this cleaning is by media blasting the valves and vacuuming the carbon out. In the past we have cleaned the valves using various chemicals and cleaning agents, but quickly found that it is not as effective as media blasting.
If you're the weekend warrior DIY type, it is entirely possible to perform this service yourself, but you will need to invest in several pieces of equipment: a media blasting tool, proper blasting media (such as walnut shells), a good air compressor, a shop vacuum, this 034Motorsport direct injection cleaning tool and some patience.
You'll also need a new intake manifold gasket and four fuel injector service kits. The fuel injector service kits contain all of the gaskets and seals required when removing the fuel injectors from the head of the engine. If you don't replace these, you might end up with a fuel leak very soon after re-installing the injectors.
You'll also need to have all the tools required to remove the intake manifold from your engine. If your water pump is in need of replacement, now is a good time to do this service since the intake manifold will be out of the way.
If you don't have all of the equipment (or feel like buying it just for this one service), have the free time available, or if you're just not that into DIY jobs and happen to be in the DMV area, please use this form to request an appointment at one of our shops. We've performed this carbon cleaning service on literally thousands of TSI engines and are more than happy to assist you with this service.
Before/After Decarbonization Service Photos
It's one thing to read about this service and its benefits, but showing you the results is even better. The images below show each of the intake ports and valves before and after the decarbonization cleaning service.
Cylinder 1:
Cylinder 2:
Cylinder 3:
Cylinder 4:
It's worth noting here that the carbon build-up I found in the Allroad was relatively mild in comparison to some of the other vehicles we've performed this service on. If I had to attribute the lack of carbon buildup on this engine to anything, it would be because it has mostly highway miles on it. The previous owner of this vehicle also used it almost exclusively for interstate driving up and down the east coast, so this makes sense. As I mentioned at the beginning, vehicles with more stop and go driving will typically have more carbon buildup than those that mostly drive on the highway.
Even though the buildup wasn't terrible on this engine, the after photos show just how much of a difference this cleaning service can make. My test drive right after the cleaning confirmed that the engine now idles much more smoothly. Another benefit, when accelerating, the throttle feels much more smooth and transitions better when stabbing it for a quick pass. These were all expected benefits, but its nice to feel the confirmation after spending an afternoon performing a service like this.
Further Carbon Buildup Cleaning and Prevention
While the service above does rectify the carbon buildup, there's another area of the engine that is affected by carbon buildup: the fuel injectors. While the injectors themselves are located within the combustion chamber and away from where the carbon buildup occurs, some of that carbon will find its way past the intake valves and into the combustion chamber. When it's bouncing around in there, the carbon material often comes in contact with the fuel injector tips and sticks to them. Over time, this can clog the fuel injector, leading to a less than optimal spray pattern.
To clean the injectors, I used the LIQUI MOLY DIJectron Gasoline System Additive. This additive uses the latest in PEA technologies to clean and prevent further buildup of carbon material on the injector. Using it is simple: add it to your fuel tank on your next fill-up and drive.
Finally, while most cleaning agents don't do a great job of breaking down the carbon once it has formed, LIQUI MOLY has developed a throttle body cleaner that can help to slow carbon from building up. This cleaner includes a flexible hose so that you can bypass the intake manifold and spray it directly onto the intake valves where the build-up occurs. While this can't completely prevent build-up from happening, it does go a long way towards slowing down the need for another decarbonization service.
Conclusion: Don't Ignore Carbon Buildup!
If you own an Audi or VW with a direct injection engine, you owe it to yourself and your car to stay on top of carbon buildup. Failure to do will lead to a loss of performance and fuel efficiency at best and severe engine damage at the worst. The service itself can be time consuming, but the benefits definitely outweigh the time it takes to do it. Remember, if you don't think you can tackle this service yourself and you're close enough to one of our shops, you can always have us do it for you. We have performed this service on literally thousands of engines and are more than happy to do it to yours. If you'd like to schedule a decarbonization service, simply fill out this form and we'll set you up with an appointment at one of our professional service centers.
Performance Coming Up Next
I know I've been covering a lot of maintenance and service information in these first updates to the project. As I mentioned in the last article, I really do live by the motto maintenance before mods. However, I am pleased to let everyone know that the next update will be focused on the performance side of the project as I dive into installing an ECU tune.